Ultrashort echo time (UTE) magnetic resonance imaging of the short T2 components in white matter of the brain using a clinical 3T scanner

• Published in: NeuroImage (Orlando, Fla.) Vol. 87; pp. 32 - 41
• Main Authors: Du, Jiang, Ma, Guolin, Li, Shihong, Carl, Michael, Szeverenyi, Nikolaus M., VandenBerg, Scott, Corey-Bloom, Jody, Bydder, Graeme M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 15.02.2014; Elsevier; Elsevier Limited
• Subjects: Adiabatic IR; Adult; Aged; Attention deficit hyperactivity disorder; Biological and medical sciences; Brain; Brain Mapping - methods; Fundamental and applied biological sciences. Psychology; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging - methods; Male; Middle Aged; Multiple sclerosis; Nerve Fibers, Myelinated; NMR; Nuclear magnetic resonance; Proton density; Studies; Ultrashort echo time; Ultrashort T2; Vertebrates: nervous system and sense organs; White matter; Adiabatic IR; Ultrashort T2; White matter; Ultrashort echo time; T2; Proton density; Central nervous system; Density; Nuclear magnetic resonance imaging; Encephalon
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1016/j.neuroimage.2013.10.053

White matter of the brain contains a majority of long T2 components as well as a minority of short T2 components. These are not detectable using clinical magnetic resonance imaging (MRI) sequences with conventional echo times (TEs). In this study we used ultrashort echo time (UTE) sequences to investigate the ultrashort T2 components in white matter of the brain and quantify their T2*s and relative proton densities (RPDs) (relative to water with a proton density of 100%) using a clinical whole body 3T scanner. An adiabatic inversion recovery prepared dual echo UTE (IR-dUTE) sequence was used for morphological imaging of the ultrashort T2 components in white matter. IR-dUTE acquisitions at a constant TR of 1000ms and a series of TIs were performed to determine the optimal TI which corresponded to the minimum signal to noise ratio (SNR) in white matter of the brain on the second echo image. T2*s of the ultrashort T2 components were quantified using mono-exponential decay fitting of the IR-dUTE signal at a series of TEs. RPD was quantified by comparing IR-dUTE signal of the ultrashort T2 components with that of a rubber phantom. Nine healthy volunteers were studied. The IR-dUTE sequence provided excellent image contrast for the ultrashort T2 components in white matter of the brain with a mean signal to noise ratio of 18.7±3.7 and a contrast to noise ratio of 14.6±2.4 between the ultrashort T2 white matter and gray matter in a 4.4min scan time with a nominal voxel size of 1.25×1.25×5.0mm3. On average a T2* value of 0.42±0.08ms and a RPD of 4.05±0.88% were demonstrated for the ultrashort T2 components in white matter of the brain of healthy volunteers at 3T. •MRI of the ultrashort T2* components in white natter of the brain is investigated.•The ultrashort T2* components are detected with 2D UTE using a clinical 3T scanner.•The contrast mechanism relies on effective suppression of the long T2 components.•IR-dUTE techniques provide robust measurement of short T2*s and proton densities.